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Sunday, March 30, 2008

Abstract: The beak of the Humboldt squid Dosidicus gigas represents one of the hardest and stiffest wholly organic materials known. As it is deeply embedded within the soft buccal envelope, the manner in which impact forces are transmitted between beak and envelope is a matter of considerable scientific interest

Here, we show that the hydrated beak exhibits a large stiffness gradient, spanning two orders of magnitude from the tip to the base. This gradient is correlated with a chemical gradient involving mixtures of chitin, water, and His-rich proteins that contain 3,4-dihydroxyphenyl-L-alanine (dopa) and undergo extensive stabilization by histidyl-dopa cross-link formation.

These findings may serve as a foundation for identifying design principles for attaching mechanically mismatched materials in engineering and biological applications.

Saturday, March 29, 2008

Researchers investigating spider species which live, feed, breed and ‘walk’ in an upside-down hanging position have found that their lifestyle drives a shape in spiders that confers high energy efficiency, as in oscillatory pendulums.

The great majority of land animals evolved legs capable of supporting the weight of their whole bodies, enabling them to move around with their heads above their feet. However, many spider species found it more convenient to literally turn their world upside down. They spend most of their lives hanging suspended by their legs, and ‘walk’ by swinging under the influence of gravity.

One of the focal questions was the evolutionary importance of ‘bridging’ – the technique many spiders use to move between remote plants by building their own silk bridges, which they cross by ‘walking’ suspended upside-down from them. Earlier research by other authors indicated that for monkeys this suspensory way of locomotion might be a more energetically efficient way of transportation than ‘regular’ walking on the ground.

“We discovered that spiders that live upside-down have evolved disproportionately longer legs relative to ‘normal’ spiders, which enables them to move faster while bridging than while ‘normally walking’ on the ground. Particularly ‘clumsy’ walkers are larger spiders, because their long legs – otherwise so convenient for bridging – do not allow an easy lifting of their relatively large body mass” says Dr. Jordi Moya-Laraño from Spain, the principal investigator on this project.

These results have implications for the evolution and ecology of spiders. For example, small spiders that hang from their webs should be able to leave their webs in search for prey by walking on the ground, as found in some tiny spiders, something that large spiders will be unable to do efficiently. link

Friday, March 28, 2008

Researchers from the Max Planck Institute for Radio Astronomy in Bonn have detected for the first time a molecule closely related to an amino acid: amino acetonitrile. The organic molecule was found in the "Large Molecule Heimat", a giant gas cloud near the galactic centre in the constellation Sagittarius.

The « Large Molecule Heimat » is a very dense, hot gas clump within the star forming region Sagittarius B2. In this source of only 0.3 light-year diameter, which is heated by a deeply embedded newly formed star, most of the interstellar molecules known to date have been found, including the most complex ones such as ethyl alcohol, formaldehyde, formic acid, acetic acid, glycol aldehyde (a basic sugar), and ethylene glycol.

Starting from 1965, more than 140 molecular species have been detected in space, in interstellar clouds as well as in circumstellar envelopes. A large fraction of these molecules is organic or carbon-based. A lot of attention is given to the quest for so-called "bio"-molecules, especially interstellar amino acids. Amino acids, the building blocks of proteins and therefore key ingredients for the origin of life, have been found in meteorites on Earth, but not yet in interstellar space.

Amino acetonitrile (NH2CH2CN)

The simplest amino acid, glycine (NH2CH2COOH), has long been searched for in the interstellar medium but has so far not been unambiguously detected. Since the search for glycine has turned out to be extremely difficult, a chemically related molecule was searched for, amino acetonitrile (NH2CH2CN), probably a direct precursor of glycine.

"Finding amino acetonitrile has greatly extended our insight into the chemistry of dense, hot star-forming regions. I am sure we will be able to identify in the future many new, even more complex organic molecules in the interstellar gas. We already have several candidates!" says Karl Menten, director at the Max Planck Institute for Radioastronomy. link

Wednesday, March 26, 2008

"The blood froze in my veins" or "My blood curdled" – these common figures of speech can be taken literally, according to the latest studies. For it turns out that intense fear and panic attacks can really make our blood clot and increase the risk of thrombosis or heart attack.

Earlier studies showed that stress and anxiety can influence coagulation.A Bonn-based research team around Franziska Geiser (from the Clinic and Policlinic for Psychosomatic Medicine and Psychotherapy) and Ursula Harbrecht (from the Institute of Experimental Haematology and Transfusion Medicine) have been the first to conduct a very careful examination of coagulation in patients with anxiety disorders.

In the coagulation system two mechanisms operate that are indispensable to life and normally work in opposite directions, each counterbalancing the other. First, coagulation involves a thickening of the blood so that a plug can form and prevent excessive bleeding from damaged vessels. Second, there is "fibrinolysis", a process that keeps the blood fluid and breaks down clots. In the case of the anxiety-disorder patients, however, the researchers observed through close analysis of the blood an activation of coagulation accompanied by an inhibition of fibrinolysis. For these types of patients, the coagulation system goes out of balance as the coagulation tendency rises – possibly with dangerous consequences. In extreme cases the imbalance can lead to blockage of a coronary artery.

The increased coagulation tendency could, says Franziska Geiser, be the "missing link" that explains why anxiety patients have a statistically higher risk of dying from heart disease by a factor of 3 or 4. link

Saturday, March 22, 2008

Tuesday, March 18, 2008

New research adds to the evidence that chance, rather than natural selection, best explains why the skulls of modern humans and ancient Neanderthals evolved differently. The findings may alter how anthropologists think about human evolution.

The study builds on findings from a study he and his colleagues published last year in the Journal of Human Evolution, in which the team compared cranial measurements of 2,524 modern human skulls and 20 Neanderthal specimens. The researchers concluded that random genetic change, or genetic drift, most likely account for the cranial differences.

In their new study, Weaver and his colleagues crunched their fossil data using sophisticated mathematical models -- and calculated that Neanderthals and modern humans split about 370,000 years ago. The estimate is very close to estimates derived by other researchers who have dated the split based on clues from ancient Neanderthal and modern-day human DNA sequences.

The close correlation of the two estimates -- one based on studying bones, one based on studying genes -- demonstrates that the fossil record and analyses of DNA sequences give a consistent picture of human evolution during this time period.

"A take-home message may be that we should reconsider the idea that all morphological (physical) changes are due to natural selection, and instead consider that some of them may be due to genetic drift," Weaver said. "This may have interesting implications for our understanding of human evolution."link

Saturday, March 15, 2008

Jean-Claude Forestcreated the character of Barbarella for V-Magazine in 1962, at the request of its editor, Georges H. Gallet, who was already familiar with Forest's work as France's premier science fiction cover artist and had commissioned an illustrated version of Catherine L. Moore's classic story Shambleau in 1955.

Barbarella was published in book for by Eric Losfeld's publishing company Le Terrain Vague in 1964, became an immediate runaway bestseller and was soon translated in a dozen countries, including by Grove Press in the United States. Not long after, it was adapted into a 1968 motion picture, produced by Dino de Laurentiis, directed by Roger Vadim, and starring Jane Fonda, for which Forest acted as design consultant.

The universe as we currently know it is made up of three dimensions of space and one of time, but researchers are exploring the possibility of an extra dimension.

“The idea we’re exploring is that the universe has an imperceptibly small dimension (about one billionth of a nanometer) in addition to the four that we know currently,” Kavic said. “This extra dimension would be curled up, in a state similar to that of the entire universe at the time of the Big Bang.”

The group is looking for small primordial black holes that, when they explode, may produce a radio pulse that could be detected here on Earth. These black holes are called primordial because they were created a fraction of a second after the beginning of the universe.

A Virginia Tech group is preparing to set up an Eight-meter-wavelength Transient Array radio telescope in Montgomery County to search the sky for these radio pulses from explosions up to 300 light years away. They have a similar telescope in southwestern North Carolina that has been looking for events for several months. link

The Hercules Beetle is remarkable, not only for its strength, able to carry up to 850 times its own weight, the protective outgrowth of the insects’ exoskeleton, also changes from green to black as its surrounding atmosphere gets more humid.

Researchers from the University of Namur in Belgium have used the latest imaging techniques to study the shell of the beetle - a scanning electronic microscope to determine the structure responsible for the colour and a spectrophotometer to analyze how the light interacts with this structure.

The light interferes with the structure to produce the green colour of the shell. When water penetrates through the widely-open porous layers, it destroys the interferences phenomenon leading to a black colouration.

As to why the beetle changes colour, question marks also remain. Some have suggested that it is to do with protection – it becomes more humid at night and is therefore good for cover to turn black. Others have suggested that it is to do with warmth absorption at night. Questions remain.

Marie Rassart, who did the research at the University of Namur, said, “The sort of structural behaviour displayed by the Hercules Beetle could be an important property for ‘intelligent’ materials’. Such materials could be put to work as humidity sensors. This could be useful for example in food processing plants to monitor the moisture level.” link